Hostname: page-component-848d4c4894-hfldf Total loading time: 0 Render date: 2024-06-10T21:04:49.672Z Has data issue: false hasContentIssue false
  • English
  • Français

Electron Microprobe Analysis of Glass Shards from Tephra Assigned to Set W, Mount St. Helens, Washington1

Published online by Cambridge University Press:  20 January 2017

Henry W. Smith ,
Rose Okazaki  and
Charles R. Knowles
Henry W. Smith
Affiliation:
Washington State University, Pullman, Washington 99164 USA
Rose Okazaki
Affiliation:
Washington State University, Pullman, Washington 99164 USA
Charles R. Knowles
Affiliation:
Idaho Bureau of Mines and Geology, Moscow, Idaho 83843 USA
Get access Rights & Permissions [Opens in a new window]

Abstract

We have extended the fallout areas for each of two members of tephra-set W, erupted from Mount St. Helens about 1500 ad , by several hundred kilometers beyond the limits mapped in 1975. We traced one member (We) east into Idaho, and the other (Wn) northeast into British Columbia. After using stratigraphic and petrographic observations to assign more than 100 tephra samples to set W, we found 26 of these, selected for chemical analysis, to be closely similar in content of Ca, Fe, and K in glass shards. But improved homogeneity was evident when the 26 sampling localities for tephra W were segregated geographically, east vs. northeast of the volcano. When Ca:Fe:K proportions were plotted on a ternary diagram, there was no overlap of the plotting areas for these two groups of tephra W samples. Without such data, tephra layers We and Wn are currently separable only from stratigraphic and geographic information. Partial glass analysis is also an aid, along with stratigraphic position and petrographic characteristics, in distinguishing tephra W from associated tephra layers. These include tephra layers T and Yn from Mount St. Helens, as well as older tephra layers from Mount Mazama and Glacier Peak.

Type
Research Article
Information
Quaternary Research , Volume 7 , Issue 2 , March 1977 , pp. 207 - 217
Copyright
University of Washington

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Footnotes

1

Scientific Paper No. 4646. College of Agriculture Research Center, Washington State University, Pullman, Washington, Project 0193.

References

Crandell, D.R. Mullineaux, D.R. (1973). Pine Creek Volcanic Assemblage at Mount St. Helens, Washington 1-23U.S. Geological Survey Bulletin 1383-AGoogle Scholar
Crandell, D.R. Mullineaux, D.R. Miller, R.D. Rubin, M. (1962). Pyroclastic Deposits of Recent Age at Mount Rainier, Washington 64-68U.S. Geological Survey Professional Paper 450-DGoogle Scholar
Crandell, D.R. Mullineaux, D.R. Rubin, M. (1975). Mount St. Helens volcano: recent and future behavior Science 187 438-441 CrossRefGoogle ScholarPubMed
Fulton, R.J. (1971). Radiocarbon Geochronology of Southern British Columbia 1-28Geological Survey of Canada Paper 71-37Google Scholar
Lawrence, D.B. (1954). Diagrammatic history of the northeast slope of Mt. St. Helens, Washington Mazama 36 41-44 Google Scholar
Lemke, R.W. Mudge, M.R. Wilcox, R.E. Powers, H.A. (1975). Geologic Setting of the Glacier Peak and Mazama Ash-Bed Markers in West-Central Montana 1-31U.S. Geological Survey Bulletin 1395-HGoogle Scholar
Marshall, A.G. (1971). An Alluvial Chronology of the Lower Palouse River Canyon and Its Relation to Archaeological Sites M.Sc. Thesis Washington State University Google Scholar
Mullineaux, D.R. (1964). Extensive Recent Pumice Lapilli and Ash Layers from Mount St. Helens Volcano, Southern Washington 285(abstract). Geological Society of America Special Paper 76Google Scholar
Mullineaux, D.R. (1974). Pumice and Other Pyroclastic Deposits in Mount Rainier National Park, Washington 1-83U.S. Geological Survey Bulletin 1326Google Scholar
Mullineaux, D.R. Hyde, J.H. Rubin, M. (1975). Widespread late glacial and postglacial tephra deposits from Mount St. Helens volcano, Washington Journal of Research of the U.S. Geological Survey 3 329-335 Google Scholar
Okazaki, R. Smith, H.W. Gilkeson, R.A. Franklin, J. (1972). Correlation of West Blacktail ash with pyroclastic layer T from the 1800 Ad eruption of Mount St. Helens Northwest Science 46 77-89 Google Scholar
Schultz, C.B. Smith, H.T.U. (1965). INQUA VIIth Congress, Guidebook for Field Conference J, Pacific Northwest The Nebraska Academy of Sciences Lincoln, Nebraska 11 Google Scholar
Smith, H.W. Okazaki, R. Aarstad, J. (1968). Recent volcanic ash in soils of northeastern Washington and northern Idaho Northwest Science 42 150-160 Google Scholar
Smith, H.W. Okazaki, R. Knowles, C.R. (1975). Electron microprobe analysis as a test of the correlation of West Blacktail ash with Mount St. Helens pyroclastic layer T Northwest Science 49 209-215 Google Scholar
Smith, H.W. Okazaki, R. Knowles, C.R. (1977). Electron microprobe data for tephra attributed to Glacier Peak, Washington Quaternary Research 7 197-206 CrossRefGoogle Scholar
Smith, D.G.W. Westgate, J.A. (1969). Electron probe technique for characterizing pyroclastic deposits Earth and Planetary Sciences Letters 5 313-319 CrossRefGoogle Scholar
Smith, D.G.W. Westgate, J.A. Tomlinson, M.C. (1969). Characterisation of pyroclastic units—a stratigraphic application of the microprobe Proceedings of the 4th National Conference on Electron Microprobe AnalysisPaper 34Google Scholar
Westgate, J.A. (1972). Recent advances in the Quaternary tephrochronology of Western Canada Geological Society of America 4 259-260(Abstracts with Programs)Google Scholar
Westgate, J.A. Fulton, R.J. (1975). Tephrostratigraphy of Olympia interglacial sediments in south-central British Columbia, Canada Canadian Journal of Earth Sciences 12 489-502 CrossRefGoogle Scholar
Westgate, J.A. Smith, D.G.W. Tomlinson, M. (1970). Late Quaternary tephra layers in southwestern Canada Proceedings 2nd Annual Paleoenvironmental Workshop of the University of Calgary Archaeological Association Vol. 2 13-34 Google Scholar
Wilcox, R.E. (1965). Volcanic-ash chronology Wright, H.E. Jr. Frey, D.G. The Quaternary of the United States Princeton Univ. Press Princeton, N.J 807-816 Google Scholar